This worm is one of the most frequently observed parasites in man. The round worm has a light brown or reddish color and a cylindrical shape. The male is 20 cm. and the female 30 cm. long. The posterior extremity of the male is bent in the form of a hook and provided with two spicules or chitinous processes. The mouth is surrounded by three muscular lips provided with very fine teeth. The sexual opening of the female lies anterior to the middle of the body (Fig. 56). The eggs when ripe have a double shell and around this is an albuminous envelope which is irregularly shaped, and studded with excrescences (Fig. 57). The long diameter of the egg is about 0.05 mm.

Ascaris Lumbricoides

Fig. 56. - Ascaris Lumbricoides. (Perls.) A, Female; B, male. (Natural size.) At a Is the female sexual oriflee; c, the two spicules of the male; b, head extremity (magnified) of the worm, with the three lips.

The round worm possesses a strong odoriferous principle which is very perceptible even after the worm has been carefully washed. According t o Huber,1 this substance may occasion urticaria in persons predisposed to this eruption. It is not improbable that certain of the symptoms of ascariasis are due to the action of the same element.

The principal habitat of ascaris lumbricoides is the small intestine of man. It develops here often in large numbers, fifty to one hundred and more occurring together. The mode of transmission, according to Leuckart, Grassi,1 and Lutz,2 is by ingestion of the eggs of the ascaris, there being no intermediate host. The full development of the round worm from the egg to its period of sexual maturity requires ten to twelve weeks. Infection usually takes place by eggs existing in the soil near dwelling-places, in the drinking-water, and also in some foods, principally salads and fruits. Ascaris lumbricoides is most frequently found in children three to twelve years old, the poorer classes showing a larger percentage than the well-to-do. In grown persons the worm is not so frequent. The female sex is more frequently infected than the male.

1 Huber: "Twentieth Century Practice of Medicine, " vol. viii., p. 583.

The diagnosis of ascariasis is made by the detection of the worm in the fecal matter, or of its eggs, which are easily recognized.

Symptoms

Ascariasis may exist without giving rise to any symptoms whatever. Occasionally, however, there are various disturbances: anorexia, nausea, irregularity of the bowel, meteorism, an irregular pulse; in children black rings around the eyes, much nervousness, even convulsions. In rare instances progressive anaemia has been observed (Leichtenstern). Anatomically hyperaemia of the intestinal wall has been frequently found, erosions are rare. Itching of the nose is often present in ascariasis and may be due to the odoriferous principle.

The round-worm is liable to wander and may then give rise to severe complications. In several instances it has been found in the bile duct, in the gall bladder, and even in the liver, producing abscesses and even a fatal issue. The worm occasionally migrates into the stomach and produces pain and often vomiting. In the latter act it is often expelled from the mouth. Occasionally it ascends the oesophagus and enters the larynx, causing asphyxia, and, in rare instances, even death. It has also been found in hernial sacs and in the peritoneal cavity, but it is generally believed that it cannot penetrate through the healthy intestinal wall. Obstruction of the bowels by a conglomeration of ascarides has also been thought possible ; its real occurrence, however, is denied by Leichten-stern.1

Egg of Ascaris Lumbricoides (Leuckart) with Shell and Albuminous Envelope

Fig. 57. - Egg of Ascaris Lumbricoides (Leuckart) with Shell and Albuminous Envelope. Magnified 300 diameters.

1 Grassi: Centralbl. f. Bacteriologie and Parasitenkunde, 1887. 2 Adolf Lutz: "Klinisches uber Parasiten des Menschen und der Hausthiere." Ceutralbl. f. Bacteriologie, 1889.

Prophylaxis requires total destruction of all the eggs of the ascaris passed with the fecal matter of the patient. The grounds near dwellings should be kept perfectly clean and the hands should be frequently washed. All foods should be protected against a possible infection.

Treatment

The treatment consists in freeing the patient from the worms. This is done in a similar manner as in the case of tapeworms. The intestinal tract is kept partially empty for a day or two before the administration of the anthelmintic. The most efficient remedy for this purpose is santonin, which is given in a dose of 0.02 to 0.06 gm. (gr. 1/3-i.) twice or four times a day. Then a purgative remedy is given. Some combine the santonin with the purgative and give them together. Thus santonin 0.2 (gr. iiiss.), castor oil 60 gm. (Treatment 81 ii.), twice or three times daily one teaspoonful for small children, a dessertspoonful for larger children, and one tablespoonful for grown people.

1 Leichtenstern: "Verengerungen. Verchliessungen und Lageveran-derungen des Darms." von Ziemssen's Hand.buch der spec. Path, und Therapie, Bd. vii., Abth. 2.

The santonin may also be given in combination with calomel; thus -

Treatment 82

Calomel..............

0.05 to 0.1

(gr. i.-ij.)

Santonin...........

0.02

(gr. 1/3)

T. d. No. ix. S. One powder three times daily.

Flores cinae, the plant from which santonin is obtained, may also be administered in doses of 0.5 to 2 gm. as powders or as an electuary, with the addition of jalap, 0.1 to 0.2 gm.

Chenopodium or wormseed is also a popular remedy, the powdered seeds being given in doses of 1 to 2 gm. (gr. xv.-xxx.), or the volatile oil in five to ten drop doses. Thymol has also been recommended in doses of 0.5 to 2 gm. (gr. vii.-xxx.) in twenty-four hours. It may be given in gelatin capsules. Irrigation of the bowels with water to which three to five drops of benzene have been added has likewise been suggested, but does not appear as beneficial as santonin.